Recently, memory systems comprising nonvolatile memories have become widespread.
As one of these memory systems, a NAND-flash solid-state drive (SSD) is known.
Because of their low-power-consumption and high-performance, SSDs are used as the main storage of various computers.
Various attempts to improve the performance of the SSDs have recently been made under control of a host.
However, in order to improve the performance of the SSDs, there is a demand for realizing a new function of providing the host with useful data for the performance improvement.